GMAT Critical Reasoning (CR) | Re: When the government taxes the sale of a particular type of good, eithe

It took >30 minutes for me to prepare the mathematical model and to understand the logic; pretty useless for GMAT exam. Nevertheless, here is:

Argument:

1. Tax(A) -> -Profit(A) OR (inclusive) +Price(A)
2. +Price(A) -> -Demand(A) AND +Demand(A-sub)
3. +Demand(X) -> +Price(X)

Now, as per logic,
(i) if a statement is true, its Contrapositive is also true.
P -> Q => ~Q -> ~P
here ~ means negation (logical opposite)
(ii) negation rules
~ (A OR B) => ~A AND ~B

Key
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